Nowadays there are a great many medical and veterinary treatments in which fluids are infused into the circulatory system of patients or animals. Very frequently, and especially when the fluids to be infused have previously been kept under refrigeration, a difference occurs between the temperature of the fluid to infuse and the body temperature of the individual to treat, and this difference is liable to disturb the thermal system of the individual and, in extreme cases, it can produce a thermal shock with sometimes lethal consequences.
So, on many occasions, as with hemorrhages occurring during operations or as a result of accidents, fluids such as blood conserves, cellular preparations or serum have to be infused into the individual very quickly. Bearing in mind that, for example, blood conserves are stored at temperatures of around 4° C., in order to avoid the negative consequences of the difference between the temperature of a blood conserve and the body temperature of the individual to whom the blood has to be administered, the conserves have to be warmed up to a temperature close to the body temperature of the individual. This, under circumstances in which an urgent and rapid administration is needed, requires a fast and efficient warming of the blood to the necessary temperature.
Moreover, in certain types of treatments and surgical operations, such as dialysis or heart surgery, extracorporeal blood circulation needs to be established in which the blood recirculated to the individual has to be kept at a constant temperature as close as possible to body temperature.
There exist devices that permit warming of physiological fluids, basically consisting of a heating apparatus which heats water to a predetermined temperature and circulates the water through a closed heat exchange device through which flows the liquid to be warmed, it collects the water from the outlet from the exchange device, reheats the water and recirculates it to the exchange device. Another type of heat exchange device for warming up physiological fluids is described, for example, in German patent DE-DE-C-827702, in European patent application EP-A-0463837 and in Spanish patent application P9700855. This type of device includes an exterior tube for the circulation of a heating fluid with a space that houses an interior tube through which the physiological fluid flows. This space is divided into a first channel through which warm fluid enters until it encounters the recirculation of heating fluid at the opposite end of the exterior tube from whose space the heating fluid enters into the second channel and returns to the heating apparatus.
Spanish patent application ES-A-2200609 describes a heat exchange device between a heating fluid and a fluid to be heated, particularly a physiological fluid, having a simple and economical structure, with a casing divided into a first compartment and a second compartment by a partition and linked by a communication passage, and with an exchange element provided in the first compartment. The heating fluid inlet discharges into the first compartment and the outlet of the heating fluid links with the second compartment, the inlet and outlet being opposite to the communication passage and provided with connector elements grouped into a dual connector for connection to complementary elements of a system for heating and recirculation of heating fluid.
Although the systems of the state of the art described above have been used in the heating of physiological fluids, they present a series of drawbacks. So, the heating of the physiological fluid has to be done via another fluid, water, which has to transfer its heat energy to the physiological fluid with the consequent energy losses and the impossibility of making any fine and immediate adjustment to the temperature at which the physiological fluid has to be infused. Also, these systems need a water circuit which, on the one hand, requires space and is relatively costly to manufacture, and, on the other, presents problems of sterility since, via micropores in joints and tubes, the water can possibly become contaminated with biological agents present in the environment.
It was therefore desirable to have a device that would permit the said drawbacks of the systems in the state of the art to be overcome.